A designed photoactive CO releasing molecule (photoCORM), namely, fac-[MnBr(CO)3(pbt)] (1, pbt = 2-(2-pyridyl)benzothiazole), promotes CO-induced death of MDA-MB-231 human breast cancer cells upon illumination with broadband visible light. The CO release from this photoCORM can be tracked by rise in fluorescence within the cellular matrix due to deligation of the pbt ligand. The results of this study suggest the potential of 1 in eradication of cancer cells through CO delivery.